Jarrod Ranney Oil Paintings

Designed by George T. Morgan, the U.S. Mint first began producing Morgan Dollars in 1878 under the Bland-Allison Act, which required that the U.S. Treasury buy a certain amount of silver and release it into circulation. After the Mint began production, they continued to produce Morgan Dollars until 1904, after which they took a 17-year hiatus until 1921 when the silver dollars were minted for one final year.

At the time of production, far more silver dollars were produced than were needed for circulation, so excess coins were stored in $1,000 U.S. Treasury canvas bags, and many of these sat untouched for decades.

What people didn’t realize until these bags were opened, however, was that some of the coins that sat near the fabric of the bags had toned beautifully over the decades that they had sat undisturbed. These bank bags had been laced with trace amounts of sulfur in order to prevent rats from ripping into them, and it was this sulfur that reacted with the silver surfaces of coins and caused a thin silver-sulfide film to form. This film refracts light and is what causes us to see beautiful colors—a phenomenon known as thin-film interference.